Data transmission and measurement techniques

ABSTRACT

Methods, systems, and devices related to related to digital wireless communication, and more specifically, to techniques related to transmitting data and feedback data between network elements is disclosed. In one exemplary aspect, a method for wireless communication includes transmitting data from a first network element to a second network element. The method also includes receiving, at the first network element, feedback data from the second network element, where the feedback data includes a highest delivered packet data convergence protocol (PDCP) sequence number (SN) and information indicative of a range of data that has been successfully delivered to a terminal. The method also includes retransmitting at least a portion of the data from the first network element based on the feedback data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2018/113619, filed on Nov. 2, 2018, the contents of which areincorporated herein by reference in its entirety.

TECHNICAL FIELD

This patent document is directed generally to digital wirelesscommunications.

BACKGROUND

Mobile communication technologies are moving the world toward anincreasingly connected and networked society. The rapid growth of mobilecommunications and advances in technology have led to greater demand forcapacity and connectivity. Other aspects, such as energy consumption,device cost, spectral efficiency, and latency are also important tomeeting the needs of various communication scenarios. Varioustechniques, including new ways to provide higher quality of service, arebeing discussed.

SUMMARY OF PARTICULAR EMBODIMENTS

This document discloses methods, systems, and devices related to digitalwireless communication, and more specifically, to techniques related totransmitting data and feedback data between network elements.

In one exemplary aspect, a method for wireless communication isdisclosed. The method includes receiving, at a transmitting data from afirst network element to a second network element; receiving, at thefirst network element, feedback data from the second network element,where the feedback data includes a highest delivered packet dataconvergence protocol (PDCP) sequence number (SN) and informationindicative of a range of data that has been successfully delivered to aterminal; and retransmitting at least a portion of the data from thefirst network element based on the feedback data.

In some embodiments, the information indicative of the range of datathat has been successfully delivered to the terminal includes a newradio user plane data (NR-U) SN.

In some embodiments, the information indicative of the range of datathat has been successfully delivered to the terminal includes the PDCPSN encapsulated within a NR-U packet data unit (PDU) and associated witha NR-U SN, where the NR-U SN is less than or equal to the NR-U SNassociated with the PDCP SN.

In some embodiments, the information indicative of the range of datathat has been successfully delivered to the terminal includes a PDU NR-USN list bit map or a PDCP PDU list bit map or one or more start and endof an PDU NR-U SN set or one or more start and end of an PDCP SN setindicating whether the data in the list bitmap or the set belongs to thefeedback data to identify multiple PDCPs. In some embodiments, thefeedback data is transmitted via a down link data feedback frame.

In some embodiments, the method includes transmitting the data includinga NR-U PDU from the first network element to the second network element;and recording the NR-U PDU and a corresponding NR-U PDU SN with a PDCPPDU encapsulated within the NR-PDU SN.

In some embodiments, the method includes transmitting data including aNR-U PDU from the first network element to the second network element;and recording a NR-U PDU and a corresponding NR-U PDU SN with a PDCPencapsulated in the NR-U PDU. In some embodiments, the method includesdelivering the data including PDCP from the first network element to thesecond network element based on the feedback data; and deleting the datacorresponding with PDCP from memory of the first network element basedon the feedback data.

In some embodiments, the method includes determining the data includingPDCP transmitted from the first network element to the second networkelement was unsuccessfully delivered to the terminal; transmitting PDUdata from the first network element to a third network element; andtransmitting the PDU data from the third network element to theterminal.

In some embodiments, the first network element is a central unit (CU) ofa base station, and the second network element is a dedicated unit (DU)of the base station.

In some embodiments, the CU and DU of the base station are connected viaa F1 interface.

In some embodiments, the first network element is a first base stationand the second network element is a second base station, where the firstnetwork element and second network element are connected via a Xn or X2interface.

In some embodiments, the method includes determining whether all PDCP SNtransmitted by the first network element are less than or equal to thehighest delivered PDCP SN in the feedback data; and determining whetherall NR-U SN transmitted by the first network element are less than orequal to the highest reported NR-U SN in the feedback data, where alltransmitted data is successfully delivered to the terminal based ondetermining that all transmitted PDCP SN are less than or equal to thehighest delivered PDCP SN and all transmitted NR-U SN are less than orequal to the highest reported NR-U SN.

In another exemplary aspect, a method for wireless communication isdisclosed. The method includes receiving, at a second network element,data from a first network element; transmitting, at the second networkelement, feedback data to the first network element, where the feedbackdata includes a highest delivered packet data convergence protocol(PDCP) sequence number (SN) and information indicative of a range ofdata that has been successfully delivered to a terminal; and receivingat least a portion of data retransmitted from the first network elementbased on the feedback data.

In some embodiments, the information indicative of the range of datathat has been successfully delivered to the terminal includes at leastone new radio user plane data (NR-U) SN.

In some embodiments, the information indicative of the range of datathat has been successfully delivered to the terminal includes the PDCPSN encapsulated within a NR-U packet data unit (PDU) associated with theNR-U SN, where the SN indicates that the NR-U SN is less than or equalto the NR-U SN associated with the PDCP SN.

In some embodiments, the information indicative of the range of datathat has been successfully delivered to the terminal indicates a PDUNR-U SN list bit map or a PDCP PDU list bit map or one or more start andend of an PDU NR-U SN set or one or more start and end of an PDCP SN setindicating whether the data in the list bitmap or set belongs to thefeedback data to identify multiple PDCPs.

In some embodiments, the feedback data is transmitted via a down linkdata feedback frame.

In some embodiments, the method including receiving NR-U PDU at thefirst network element from the second network element; and recording aNR-PDU and a corresponding NR-U PDU SN with a PDCP PDU encapsulatedwithin the NR-PDU SN.

In some embodiments, the method including receiving NR-U PDU at thefirst network element from the second network element; and recording aNR-U PDU and a corresponding NR-U PDU SN with the PDCP encapsulated inthe NR-U PDU.

In some embodiments, the method includes determining whether NR-U PDUtransmitted from the first network element to the second network elementis retransmission data; and transmitting the retransmission data fromthe second network element to the terminal based on determining that theNR-U PDU transmitted from the first network element to the secondnetwork element is retransmission data.

In some embodiments, the method includes receiving data at the secondnetwork element from the first network element, where the data includesat least two NR-U PDUs, and where each of the at least two NR-U PDUsinclude PDCP SN encapsulated in the NR-U PDU; reordering the NR-U PDUsbased on PDCP SN sequence at the second network element; andtransmitting the ordered NR-U PDUs to the terminal.

In some embodiments, the method includes determining whether all PDCP SNtransmitted by the first network element are less than or equal to thehighest delivered PDCP SN in the feedback data; and determining whetherall NR-U SN transmitted by the first network element are less than orequal to the highest reported NR-U SN in the feedback data, where alltransmitted data is successfully delivered to the terminal based ondetermining that all transmitted PDCP SN are less than or equal to thehighest delivered PDCP SN and all transmitted NR-U SN are less than orequal to the highest reported NR-U SN.

In some embodiments, the method includes receiving data including PDCPfrom the first network element to the second network element based onthe feedback data; and deleting the data corresponding with PDCP that islocally stored at the first network element based on the feedback data.In some embodiments, the method includes determining that the PDCPtransmitted from the first network element to the second network elementwas unsuccessfully delivered to the terminal; transmitting the PDU datafrom a first network element to a third network element; andtransmitting the PDU data from the third network element to theterminal.

In some embodiments, the first network element is a central unit (CU) ofa base station, and the second network element is a dedicated unit (DU)of the base station.

In some embodiments, the CU and DU of the base station are connected viaan F1 interface.

In some embodiments, the first network element is a first base stationand the second network element is a second base station, where the firstnetwork element and second network element are connected via a Xn or X2interface.

In some embodiments, including a second terminal connected to the firstnetwork element and a network element connected to a plurality of basestations.

In another exemplary aspect, a wireless communications apparatuscomprising a processor is disclosed. The processor is configured toimplement a method described herein.

In yet another exemplary aspect, the various techniques described hereinmay be embodied as processor-executable code and stored on acomputer-readable program medium.

The details of one or more implementations are set forth in theaccompanying attachments, the drawings, and the description below. Otherfeatures will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary schematic diagram of a system architecture forDual Connectivity (DC).

FIG. 2 shows an example of transmission of user plane data betweennetwork elements.

FIG. 3 shows an example of transmission of feedback data between networkelements.

FIG. 4 shows an example of a wireless communication system wheretechniques in accordance with one or more embodiments of the presenttechnology can be applied.

FIG. 5 is a block diagram representation of a portion of a radiostation.

FIG. 6 shows an exemplary downlink data feedback frame for RLCacknowledged mode (AM).

FIG. 7 shows an exemplary downlink data feedback frame for RLCunacknowledged mode (UM).

FIG. 8 shows a flow chart representation of a method for wirelesscommunication.

FIG. 9 shows an exemplary process of transmitting a feedback messagebetween network elements.

DETAILED DESCRIPTION

This patent document relates to wireless communications and, moreparticularly to providing downlink feedback information based on datatransmitted between network elements (NEs) in a wireless communicationsnetwork.

The development of the new generation of wireless communication—5G NewRadio (NR) communication—is a part of a continuous mobile broadbandevolution process to meet the requirements of increasing network demand.NR will provide greater throughput to allow more users connected at thesame time. Other aspects, such as energy consumption, device cost,spectral efficiency, and latency are also important to meeting the needsof various communication scenarios. As NR emerges in the wirelessdomain, UEs will be capable of supporting both protocols at the sametime.

FIG. 1 shows an exemplary schematic diagram of a system architecture forDual Connectivity (DC). The current base station (referred to as thefirst network element 101) in the core network 103 may select a suitablebase station for the UE 100 to function as the second network element102. For example, the suitable based station can be selected bycomparing the channel quality of the base station with a predeterminedthreshold. Both base stations can provide radio resources to the UE 100for data transmission on the user plane. On the wired interface side,the first network element 101 and the core network 103 establish acontrol plane interface 104 for the UE 100. The second network element102 and the core network 103 may establish a user plane interface 105for the UE 100.

An interface 106 (e.g., Xn interface) inter-connects the two networkelements. The communication interface between 5G-capable networkelements (gNB) may include an Xn interface. The interface between a5G-capable network element (gNB) and a non-5G network element (e.g.,eNB) may include an X2 interface. 5G supports the transfer of databetween base stations via the Xn or X2 interfaces.

On the wireless interface side, the first and the second networkelements (101 and 102) may provide radio resources using the same ordifferent Radio Access Technologies (RATs). Each of the network elementcan schedule transmissions with the UE 100 independently. The networkelement that has a control plane connection to the core network isreferred to as the master node (e.g., the first network element 101),and the network element that has only a user plane connection with thecore network is referred to as the secondary node (e.g., the secondnetwork element 102). In some cases, the UE 100 can be connected to morethan two nodes, with one node acting as the primary note and theremaining acting as the secondary nodes.

In some embodiments, a UE can support a LTE-NR dual connection (DC). Forexample, one of the typical LTE-NR dual connectivity architectures canbe set up as follows: the master node is an LTE RAN node (e.g., eNB) andthe secondary node is an NR RAN node (e.g., gNB). The eNB and the gNBare simultaneously connected the Evolved Packet Core (EPC) network(e.g., LTE core network). The architecture shown in FIG. 1 can also bemodified to include various master/secondary node configurations. Forexample, a NR RAN node can be the master node and the LTE RAN node canbe the secondary node. In such case, the core network for the master NRRAN node is a Next Generation Converged Network (NG-CN).

UE capabilities for the LTE protocol and the NR protocol in LTE-NR DCinclude two parts: common capabilities of the UE that are applicable toboth LTE and NR protocols for single connectivity scenarios, and bandcombination capabilities of the UE that are relevant for dualconnectivity scenarios. When the UE has multiple simultaneousconnections with network nodes, the frequency bands used for differentnetwork nodes must cooperate with each other regardless of the RATtype(s) used. Here, the term “cooperate” means that the UE can operatein the frequency bands without any conflicts or substantialinterference—that is, the frequency bands can co-exist. For example, the3rd Generation Partnership Project (3GPP) Standards specify a set ofband combinations that can cooperate with each other. If frequency band1 and frequency band 2 are not specified as a valid band combination,the UE cannot use frequency band 1 in communication with node 1 andfrequency band 2 in communication with node 2 and the same time.

A interface (Xn, X2) may include at least two planes: A control planeand a user plane. For example, the Xn/X2 control plane may be referredto as Xn-C/X2-C, and the user plane may be referred to as Xn-U/X2-U. Thecontrol plane (Xn-C/X2-C) may be used to transmit control planeinformation between base stations (gNB) and facilitate control planefunctionality between base stations. The user plane (Xn-U/X2-U) maytransmit user plane data and transmission status data between basestations (gNB).

In some embodiments, a 5G base station (gNB) supports central unit anddedicated unit separation architecture. Such a separation architecturemay include a base station (gNB) with one centralized unit (gNB-CU) andone or more distributed units (gNB-DU). 5G supports internal basestation data transmission between the gNB-CU and gNB-DU using an F1interface.

The gNB-CU may control one or more gNB-DUs via an F1 interface. The F1interface may be include a F1 Control plane (F1-C) and a F1 user plane(F1-U). F1-C may transmit control plane information to facilitate gNB-CUto gNB-DU control plane functionality. F1-U may transmit user plane dataand transmission status feedback data.

FIG. 2 shows an example of transmission of user plane data betweennetwork elements. In this example, a first network element 201 transmitsa message 203 to a second network element 205. Examples of a networkelement may include a base station (eNB, gNB) or a unit within a basestation (CU, DU). A network element may include packet data convergenceprotocol (PDCP), and in the embodiment as shown in FIG. 2, the firstnetwork element 201 may include PDCP. A network element may includeradio link control (RLC), and in the embodiment as shown in FIG. 2, thesecond network element 205 may include RLC.

As shown in FIG. 2, the first network element (PDCP) 201 may transmit NRuser plane data (NR-U) to the second network element (RLC) 205, wherethe NR-U data may be transmitted via one or more packet data units(PDUs). A NR-U PDU may be transmitted between network elements using theXn-U, X2-U, or the F1-U interface.

In some embodiments, the first network element 201 is a gNB-CU andincludes PDCP, and the second network element 205 is a gNB-DU thatincludes RLC. In these embodiments, the gNB-CU and gNB-DU may beconnected via a F1 interface. In other embodiments, each network elementis a base station (e.g., eNB, gNB), and the connection between basestations may include a X2/Xn interface.

On the user plane of an interface (F1-U, Xn-U, X2-U), the underlyingdata transport layer protocol may be based on GPRS Tunneling ProtocolUser Plane (GTP-U). The message 203 may include PDCP PDU using GTP-U.Each GTP-U user plane packet may include a GTP-U header and a tunnel PDUfield (T-PDU field), where a GTP-U tunnel is used to transport anencapsulated T-PDU between GTP-U tunnel endpoints. A GTP-U packet mayinclude a GTP-U header and T-PDU field.

In some embodiments, GTP-U may include an extended header structure. TheIE defined by the interface PDU of the user plane may be carried by theextended header of the GTP-U. The transmitted GTP-U packet data maycomprise NR-U PDU. One or more NR-U PDUs are sent on the NR-U interface.In some embodiments, a PDCP PDU may be encapsulated in an NR-U PDU.

A series of NR-U PDUs may be transmitted sequentially from the firstnetwork element and in a specific order. In some embodiments, each NR-UPDU includes a PDCP SN and a NR-U SN. Generally, the first networkelement 201 sends PDCP PDU data to the second network element 205, whereeach PDCP PDU is encapsulated in an NR-U PDU. A series of NR-U PDUs maybe sent sequentially by an increasing PDCP SN sequence number. In someembodiments, a PDCP SN may be transmitted to the terminal sequentially,where each PDCP SN corresponds with a NR-U SN. A terminal (e.g., UE) mayreceive the NR-U PDUs in the sequential order, where the sequentialorder may include each PDCP PDU transmitted by increasing PDCP SNnumber.

In some embodiments, the first network element may transmit NR-U PDU tothe second network element 305 and record the NR-PDU and a correspondingNR-U PDU SN with a PDCP PDU encapsulated within the NR-PDU SN.Additionally, the first network element 301 may transmit NR-U PDU to thesecond network element and record the NR-PDU and a corresponding NR-UPDU SN with a PDCP encapsulated within the NR-U PDU

FIG. 3 shows an example of transmission of feedback data between networkelements. As illustrated in FIG. 3, a first network element 301 mayinclude a node hosting NR PDCP, and the second network element 305 mayhost a corresponding node. The first network element 301 may transmitdata to a second network element 305, such as a node where the RLC islocated. The data may include NR-U PDU data, where each NR-U PDU mayinclude a PDCP SN and an NR-U SN.

As shown in FIG. 3, the second network element 305 may transmit data tothe terminal 309 via terminal message 311. In some embodiments, theterminal 309 may include a UE. All data transmitted to the terminal 309via terminal message 311 and received by the terminal 309 may bereferred to as successfully delivered data.

In some embodiments, the second network element 305 may transmit afeedback message 307 to the first network element 301. The feedbackmessage 307 may be in the downlink (DL) data. The feedback message 307may indicate the data transmission state to the first network element301 in the downlink feedback frame (e.g. DL data delivery status). Thefirst network element 301 may receive the downlink data in the downlinkdata feedback frame of the feedback message 307, where the feedbackratio is the highest delivered PDCP SN that indicates the maximum PDCPSN of the PDCP PDU that was successfully delivered to the terminal 309.

The DL data delivery status of the feedback message 307 may indicatewhether some or all of the data was successfully delivered to theterminal 309. In some embodiments, the first network element 301receives the feedback message 307 from the second network element 305,where the feedback message 307 indicates whether some or all of the PDCPdata was successfully transmitted to the terminal 309. Successfultransmission of a PDCP may include the PDCP transmitted by the firstnetwork element 301 successfully delivered to the terminal 309 viaterminal message 311. In these embodiments, the data associated with thesuccessfully delivered PDCP PDUs may be deleted from the memory (e.g.,cache memory) of the first network element 301.

In some embodiments, the first network element 301 may receive data inthe feedback message 307 that indicates at least some PDCP were notsuccessfully transmitted. In these embodiments, the PDCP transmittedfrom the first network element 301 was not successfully delivered to theterminal 309.

In the event of unsuccessful delivery to the terminal 309, the firstnetwork element 301 may retransmit at least a portion of the PDCP PDUdata to the second network element 305 in a retransmission message 313.Generally, the first network element 301 sends PDCP PDU data to thesecond network element 305, where each PDCP PDU is encapsulated in anNR-U PDU.

In the feedback message 307 to the first network element 301, the secondnetwork element 305 may transmit the greatest numbered PDCP SN that wassuccessfully sent to the terminal. In other words, the greatest PDCP SNin a sequence of PDCP PDUs that was successfully delivered to theterminal 309 is transmitted in the feedback message 307. Generally, thehighest delivered PDCP SN may indicate where the successful transmissionof the data to the terminal 309 ends. Any PDCP PDU with a PDCP SNgreater than the highest delivered PDCP SN may be out of order orundelivered to the terminal 309.

If the first network element 301 transmits PDCP with corresponding PDUsto the second network element 305 that are out of order, the data maynot be transmitted in order over the interface (e.g., Xn, X2, F1). Inthe existing feedback method, indicating only one of the largestconsecutively delivered PDCP SNs cannot respond to the delivery of theout of order data. Accordingly, existing network elements cannotdetermine what data was successfully transmitted to the terminal 309. Insome embodiments, the first network element 301 may delete the PDU fromits memory if the first network element 301 determines that the PDU wassuccessfully delivered. Also, the first network element may 301 maydetermine that PDCP was not delivered successfully and the PDU must beretransmitted from via retransmission message 313 to deliver the PDU tothe terminal 309.

This patent document describes techniques that can be implemented toprovide feedback to a network element that includes both a highestdelivered PDCP SN and information indicative of a range of data that hasbeen successfully delivered to a terminal. The first network canidentify any undelivered data and retransmit any data that wasunsuccessfully delivered in a proper order based on both the highestdelivered PDCP SN and information indicative of the range of data thathas been successfully delivered to the terminal.

FIG. 4 shows an example of a wireless communication system wheretechniques in accordance with one or more embodiments of the presenttechnology can be applied. A wireless communication system 400 caninclude one or more base stations (BSs) 405 a, 405 b, one or morewireless devices 410 a, 410 b, 410 c, 410 d, and a core network 425. Abase station 405 a, 405 b can provide wireless service to wirelessdevices 410 a, 410 b, 410 c and 410 d in one or more wireless sectors.In some implementations, a base station 405 a, 405 b includesdirectional antennas to produce two or more directional beams to providewireless coverage in different sectors.

The core network 425 can communicate with one or more base stations 405a, 405 b. The core network 425 provides connectivity with other wirelesscommunication systems and wired communication systems. The core networkmay include one or more service subscription databases to storeinformation related to the subscribed wireless devices 410 a, 410 b, 410c, and 410 d. A first base station 405 a can provide wireless servicebased on a first radio access technology, whereas a second base station405 b can provide wireless service based on a second radio accesstechnology. The base stations 405 a and 405 b may be co-located or maybe separately installed in the field according to the deploymentscenario. The wireless devices 410 a, 410 b, 410 c, and 410 d cansupport multiple different radio access technologies.

In some implementations, a wireless communication system can includemultiple networks using different wireless technologies. A dual-mode ormulti-mode wireless device includes two or more wireless technologiesthat could be used to connect to different wireless networks.

FIG. 5 is a block diagram representation of a portion of a radiostation. A radio station 505 such as a base station or a wireless device(or UE) can include processor electronics 510 such as a microprocessorthat implements one or more of the wireless techniques presented in thisdocument. The radio station 505 can include transceiver electronics 515to send and/or receive wireless signals over one or more communicationinterfaces such as antenna 520. The radio station 505 can include othercommunication interfaces for transmitting and receiving data. Radiostation 505 can include one or more memories (not explicitly shown)configured to store information such as data and/or instructions. Insome implementations, the processor electronics 510 can include at leasta portion of the transceiver electronics 515. In some embodiments, atleast some of the disclosed techniques, modules or functions areimplemented using the radio station 505.

Example Embodiment 1

FIG. 6 shows an exemplary downlink data feedback frame for RLCacknowledged mode (AM). In this embodiment, the downlink data feedbackframe is for a RLC AM feedback message. The feedback message may betransmitted to the first network element, where the first networkelement may retransmit data based on the contents of the feedbackmessage. In the downlink data feedback frame, only portions of datarelating to the transmission state feedback are described. Otherportions of the data may be omitted from the present disclosure.

RLC AM mode generally includes the terminal transmitting a messagerepresenting an acknowledgement that the terminal successfully receiveddata. In RLC AM mode, when the feedback data is transmitted to the firstnetwork element, the highest successfully delivered retransmitted NRPDCP SN and information indicative of a range of data that has beensuccessfully delivered to a terminal may be included in the feedbackmessage.

The highest successfully delivered retransmitted NR PDCP SN may includeretransmitted data from the first network element to deliver the maximumPDCP SN that was successfully delivered to the terminal. For example,the NR PDCP SN may indicate the highest SN that was successfullydelivered among the retransmission data PDCP that was transmitted fromthe first network element to the second network element. The firstnetwork element may retransmit data in order to deliver the highest PDCPSN.

Information indicative of a range of data that has been successfullydelivered to a terminal may include the highest reported NR-U SN thatwas successfully delivered to the terminal. The highest reported NR-U SNmay be used to indicate the scope of the report for the retransmissionof data. In some embodiments, the information indicative of a range ofdata that has been successfully delivered to a terminal may include PDCPSN encapsulated within a NR-U PDU associated with the NR-U SN, where theSN indicates that the NR-U SN is less than or equal to the NR-U SNassociated with the PDCP SN. In some embodiments, the informationindicative of the range of data that has been successfully delivered tothe terminal includes a PDU NR-U SN list bit map or a PDCP PDU list bitmap or one or more start and end of an PDU NR-U SN set or one or morestart and end of an PDCP SN set indicating whether the data in the listbitmap or the set belongs to the feedback data to identify multiplePDCPs.

The highest successfully delivered retransmitted NR PDCP SN andinformation indicative of a range of data that has been successfullydelivered to a terminal may indicate what data was successfullytransmitted to the terminal. In an example, the first network elementtransmits data representing one or more PDCP PDUs to the second networkelement. The second network element transmits the data to the terminal,where the terminal acknowledged that the data was successfully deliveredto the terminal.

Accordingly, in the feedback message, the second network elementtransmits the highest successfully delivered retransmitted NR PDCP SNand information indicative of a range of data that has been successfullydelivered to the terminal to the first network element. The firstnetwork element may determine that the highest PDCP SN received was thegreatest PDCP SN in the PDCP SN sequence that was transmitted.Similarly, the first network element may determine that the informationindicative of a range of data that has been successfully delivered tothe terminal (e.g., the highest reported NR-U SN) was the highest SN ina sequence of SNs that was transmitted.

The first network element may determine that all transmitted PDCP SNsare less than or equal to the highest reported PDCP SN to determine thatall transmitted PDCP PDUs were successfully delivered to the terminal.Similarly, the first network element may determine that all NR-U SNs areless than or equal to the highest reported SN to determine that alltransmitted PDCP PDUs were successfully delivered to the terminal. Inthis embodiment, the first network element may determine that all PDCPPDUs were successfully delivered to the terminal.

In some embodiments, the PDCP transmitted from the first network elementto the second network element may be unsuccessfully delivered to theterminal. In these embodiments, the first network element may transmitthe PDU data to a third network element, such as a base station. Thethird network element may then transmit the PDU data to the terminal.

In another example, in the feedback message, the second network elementtransmits the highest successfully delivered retransmitted NR PDCP SNand information indicative of a range of data that has been successfullydelivered to the terminal to the first network element to the firstnetwork element. In an example, the first network element may determinethat the highest PDCP SN received was not the greatest PDCP SN in thePDCP SN sequence that was transmitted. In this example, a PDCP SNcorresponding to a PDCP PDU transmitted from the first network elementmay be greater than the highest delivered PDCP SN in the feedbackmessage. The first network element may determine that some PDCP PDUswere unsuccessfully delivered, as a PDCP SN of a transmitted PDCP PDU isgreater than the highest delivered PDCP SN in the feedback message.However, looking only at the highest delivered PDCP SN, it may beunclear what PDCP PDUs were unsuccessfully transmitted to the terminal.

Similarly, the first network element may determine that the informationindicative of a range of data that has been successfully delivered tothe terminal (e.g., the highest NR-U SN reported) was not the greatestNR-U SN in the sequence that was transmitted, as a transmitted NR-U SNis greater than the highest reported NR-U SN. In this example, the firstnetwork element may determine that at least some PDCP PDUs with acorresponding NR-U SN greater than the highest reported NR-U SN shouldbe retransmitted. Determining what data to retransmit based on thehighest delivered PDCP SN and information indicative of a range of datathat has been successfully delivered to the terminal may allow for datato be retransmitted properly and in order.

Example Embodiment 2

FIG. 7 shows an exemplary downlink data feedback frame for RLCunacknowledged mode (UM). In this embodiment, the downlink data feedbackframe is for a RLC UM feedback message. In RLC unacknowledged mode, RLCUM is a non-confirmed delivery (i.e. the NE does not know whether the UMdata is delivered to the terminal) mode, so the network element onlyfeeds back whether the UM mode data is successfully delivered to theunderlying MAC/PHY layer.

The feedback message as shown in FIG. 7 may be transmitted to the firstnetwork element, where the first network element may retransmit databased on the feedback message. In the downlink data feedback frame, onlyportions of data relating to the transmission state feedback aredescribed. Other portions of the data may be omitted from the presentdisclosure.

When the feedback message is transmitted to the first network module,the feedback message may include the highest retransmitted NR PDCP SNand information indicative of a range of data that has been successfullydelivered to the terminal (e.g., highest reported NR-U SN) to feedbackwhether the data is successfully delivered to the MAC/PHY layer. Theinformation indicative of a range of data that has been successfullydelivered to the terminal may include a highest reported NR PDCP SN, andthe first network element may map the NR PDCP SN with a correspondingPDCP SN and NR-U SN.

In some embodiments, the first network element may determine whether thetransmitted PDCP SNs are less than or equal to the highest reported PDCPSN. If all transmitted PDCP SNs are less than or equal to the highestreported PDCP SN, all PDCP PDUs were successfully delivered. If atransmitted PDCP SN is greater than the highest reported PDCP SN, atleast a portion of the PDCP PDUs were not successfully delivered to theterminal.

Similarly, the first network element may determine whether the NR-U SNsof the transmitted data are less than or equal to the informationindicative of a range of data that has been successfully delivered tothe terminal (e.g., highest reported NR-U SN). If all transmitted NR-USNs are less than or equal to the highest reported NR-U SN, all PDCPPDUs were successfully delivered. If a transmitted NR-U SN is greaterthan the highest reported NR-U SN, at least a portion of the PDCP PDUswere not successfully delivered to the terminal.

Example Embodiment 3

FIG. 8 shows a flow chart representation of a method 800 for wirelesscommunication. The method 800 includes, at 802, transmitting data from afirst network element to a second network element. The method 800 alsoincludes, at 804, receiving, at the first network element, feedback datafrom the second network element, where the feedback data includes ahighest delivered packet data convergence protocol (PDCP) sequencenumber (SN) and information indicative of a range of data that has beensuccessfully delivered to a terminal. The method 800 also includes, at806, retransmitting at least a portion of the data from the firstnetwork element based on the feedback data.

In some embodiments, the method 800 may include performing data deletionfrom memory of the first network element and data retransmissionaccording to the feedback message. The first network element may receivethe retransmission data transmission status in the feedback message, andthe data that was successfully transmitted may be deleted from the firstnetwork element. Data that was not successfully delivered, as indicatedin the feedback message, is retransmitted, thereby deleting the memoryof the first network element and ensuring reliability of the datatransmission.

Example Embodiment 4

FIG. 9 shows an exemplary process of transmitting a feedback messagebetween network elements. As shown in FIG. 9, data is transmitted from afirst network element to a second network element. In some embodiments,the first network element is a CU of a base station, and the secondnetwork element is a DU of the base station.

In some embodiments, the data includes one or more PDCP PDUs. As shownin FIG. 9, the CU may transmit PDCP PDUs in the following order:#102(15), #104(16), #95(17), #96(18), #97(19), where each PDU isrepresented by # PDCP SN (NR-U SN). For example, #102(15) has a PDCP SNof 102 and a NR-U SN of 15.

Generally, data transmitted to the terminal is ordered sequentially byPDCP SN. In this example, however, the data transmitted is out of order,as PDCP SN #104 was transmitted ahead of PDCP SN #95, #96, and #97. Thedata may be transmitted out of order for a variety of reasons, such asinterface delay or interference, for example. In this embodiment, if thedata is received out of order, the terminal may only successfullyreceive #102(15), #104(16), and the terminal may fail to successfullyreceive #95(17), #96(18), #97(19). The second network element mayreorder any out of order data. In some embodiments, the second networkelement may reorder PDCP PDUs by consecutive PDCP SN numbers, where thePDU with the lowest received PDCP SN is ordered first, and the PDU withthe greatest received PDCP SN is ordered last. In other embodiments, thePDUs may be ordered by NR-U SN. The second network element may transmitthe ordered PDUs in a terminal message to the terminal.

The second network element may transmit a feedback message to the firstnetwork element based on the data successfully delivered to theterminal, where the feedback message includes the highest delivered PDCPSN and information indicative of a range of data delivered to theterminal. In this embodiment, the highest delivered PDCP SN is 104, thegreatest PDCP SN number successfully delivered to the terminal.Additionally, in this embodiment, the information indicative of a rangeof data delivered to the terminal, the highest reported NR-U SN, is 16.

Upon receipt of the feedback message, the first network element maydetermine that the highest delivered PDCP SN was 104 and the highestreported NR-U SN was 16. The first network element may determine thatall PDCP SNs transmitted were less than or equal to 104. In conventionalsystems, viewing the highest PDCP SN alone may leave confusion as towhether all PDCP PDUs were successfully delivered to the terminal.

In some embodiments, the first network element may determine whether alltransmitted NR-U SN were less than or equal to the highest reported NR-USN (16). However, in this example, the transmitted NR-U SNs includenumbers ranging from 17 to 19. The first network element may determinethat the transmitted NR-U SNs (17 to 19) are greater than the highestreported NR-U SN (16), and accordingly, the first network element maydetermine that #95(17), #96(18), #97(19) failed to successfully deliverto the terminal.

In response to the above determinations, the first network element mayretransmit all or part of the data to the second network element. If thesecond network element transmits a feedback message to the first networkelement including a highest delivered PDCP SN and highest reported NR-USN, the first network element may determine that the transmitted dataincludes PDCP SNs and NR-U SNs less than or equal to the highestdelivered PDCP SN and highest reported NR-U SN. The first networkelement may then determine that all data was successfully delivered tothe terminal.

From the foregoing, it will be appreciated that specific embodiments ofthe presently disclosed technology have been described herein forpurposes of illustration, but that various modifications may be madewithout deviating from the scope of the invention. Accordingly, thepresently disclosed technology is not limited except as by the appendedclaims.

The disclosed and other embodiments, modules and the functionaloperations described in this document can be implemented in digitalelectronic circuitry, or in computer software, firmware, or hardware,including the structures disclosed in this document and their structuralequivalents, or in combinations of one or more of them. The disclosedand other embodiments can be implemented as one or more computer programproducts, i.e., one or more modules of computer program instructionsencoded on a computer readable medium for execution by, or to controlthe operation of, data processing apparatus. The computer readablemedium can be a machine-readable storage device, a machine-readablestorage substrate, a memory device, a composition of matter effecting amachine-readable propagated signal, or a combination of one or morethem. The term “data processing apparatus” encompasses all apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, or multiple processors or computers.The apparatus can include, in addition to hardware, code that creates anexecution environment for the computer program in question, e.g., codethat constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, or a combination of one or moreof them. A propagated signal is an artificially generated signal, e.g.,a machine-generated electrical, optical, or electromagnetic signal, thatis generated to encode information for transmission to suitable receiverapparatus.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this document can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Computer readable media suitable for storingcomputer program instructions and data include all forms of non-volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks;magneto optical disks; and CD ROM and DVD-ROM disks. The processor andthe memory can be supplemented by, or incorporated in, special purposelogic circuitry.

While this patent document contains many specifics, these should not beconstrued as limitations on the scope of any invention or of what may beclaimed, but rather as descriptions of features that may be specific toparticular embodiments of particular inventions. Certain features thatare described in this patent document in the context of separateembodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described in this patent document should not be understoodas requiring such separation in all embodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document.

What is claimed is:
 1. A method for wireless communication, comprising:transmitting data from a first network element to a second networkelement; receiving, at the first network element, feedback data from thesecond network element, where the feedback data includes a highestdelivered packet data convergence protocol (PDCP) sequence number (SN)and information indicative of a range of data that has been successfullydelivered to a terminal; and retransmitting at least a portion of thedata from the first network element based on the feedback data.
 2. Themethod of claim 1, where the information indicative of the range of datathat has been successfully delivered to the terminal includes a highestreported new radio user plane data (NR-U) SN successfully delivered tothe terminal.
 3. The method of claim 2, where the information indicativeof the range of data that has been successfully delivered to theterminal includes a PDCP SN encapsulated within a NR-U packet data unit(PDU) and associated with a NR-U SN, where the highest reported NR-U SNis less than or equal to the NR-U SN associated with the PDCP SN.
 4. Themethod of claim 1, where the information indicative of the range of datathat has been successfully delivered to the terminal includes start andend of an PDU NR-U SN set indicating whether the data in the set belongsto the feedback data to identify multiple PDCPs.
 5. The method of claim2, further including: determining whether all PDCP SN transmitted by thefirst network element are less than or equal to the highest deliveredPDCP SN in the feedback data; and determining whether all NR-U SNtransmitted by the first network element are less than or equal to thehighest reported NR-U SN in the feedback data, where all transmitteddata is successfully delivered to the terminal based on determining thatall transmitted PDCP SN are less than or equal to the highest deliveredPDCP SN and all transmitted NR-U SN are less than or equal to thehighest reported NR-U SN.
 6. A method for wireless communication,comprising: receiving, at a second network element, data from a firstnetwork element; transmitting, at the second network element, feedbackdata to the first network element, where the feedback data includes ahighest delivered packet data convergence protocol (PDCP) sequencenumber (SN) and information indicative of a range of data that has beensuccessfully delivered to a terminal; and receiving at least a portionof data retransmitted from the first network element based on thefeedback data.
 7. The method of claim 6, where the informationindicative of the range of data that has been successfully delivered tothe terminal includes at least one highest reported new radio user planedata (NR-U) SN successfully delivered to the terminal.
 8. The method ofclaim 7, where the information indicative of the range of data that hasbeen successfully delivered to the terminal includes a PDCP SNencapsulated within a NR-U packet data unit (PDU) associated with theNR-U SN, where the highest reported NR-U SN is less than or equal to theNR-U SN associated with the PDCP SN.
 9. The method of claim 6, where theinformation indicative of the range of data that has been successfullydelivered to the terminal indicates start and end of an PDU NR-U SN setindicating whether the data in the set belongs to the feedback data toidentify multiple PDCPs.
 10. The method of claims 7, further including:determining whether all PDCP SN transmitted by the first network elementare less than or equal to the highest delivered PDCP SN in the feedbackdata; and determining whether all NR-U SN transmitted by the firstnetwork element are less than or equal to the highest reported NR-U SNin the feedback data, where all transmitted data is successfullydelivered to the terminal based on determining that all transmitted PDCPSN are less than or equal to the highest delivered PDCP SN and alltransmitted NR-U SN are less than or equal to the highest reported NR-USN.
 11. An apparatus for wireless communication comprising a processorthat is configured to perform a method, the processor being configuredto: transmit data from a first network element to a second networkelement; receive, at the first network element, feedback data from thesecond network element, where the feedback data includes a highestdelivered packet data convergence protocol (PDCP) sequence number (SN)and information indicative of a range of data that has been successfullydelivered to a terminal; and retransmit at least a portion of the datafrom the first network element based on the feedback data.
 12. Theapparatus of claim 11, where the information indicative of the range ofdata that has been successfully delivered to the terminal includes ahighest reported new radio user plane data (NR-U) SN successfullydelivered to the terminal.
 13. The apparatus of claim 12, where theinformation indicative of the range of data that has been successfullydelivered to the terminal includes a PDCP SN encapsulated within a NR-Upacket data unit (PDU) and associated with a NR-U SN, where the highestreported NR-U SN is less than or equal to the NR-U SN associated withthe PDCP SN.
 14. The apparatus of claim 11, where the informationindicative of the range of data that has been successfully delivered tothe terminal includes start and end of an PDU NR-U SN set indicatingwhether the data in the set belongs to the feedback data to identifymultiple PDCPs.
 15. The apparatus of claim 12, wherein the processor isfurther configured to: determine whether all PDCP SN transmitted by thefirst network element are less than or equal to the highest deliveredPDCP SN in the feedback data; and determine whether all NR-U SNtransmitted by the first network element are less than or equal to thehighest reported NR-U SN in the feedback data, where all transmitteddata is successfully delivered to the terminal based on a determinationthat all transmitted PDCP SN are less than or equal to the highestdelivered PDCP SN and all transmitted NR-U SN are less than or equal tothe highest reported NR-U SN.
 16. An apparatus for wirelesscommunication comprising a processor that is configured to perform amethod, the processor being configured to: receive, at a second networkelement, data from a first network element; transmit, at the secondnetwork element, feedback data to the first network element, where thefeedback data includes a highest delivered packet data convergenceprotocol (PDCP) sequence number (SN) and information indicative of arange of data that has been successfully delivered to a terminal; andreceive at least a portion of data retransmitted from the first networkelement based on the feedback data.
 17. The apparatus of claim 16, wherethe information indicative of the range of data that has beensuccessfully delivered to the terminal includes at least one highestreported new radio user plane data (NR-U) SN successfully delivered tothe terminal.
 18. The apparatus of claim 17, where the informationindicative of the range of data that has been successfully delivered tothe terminal includes a PDCP SN encapsulated within a NR-U packet dataunit (PDU) associated with the NR-U SN, where the highest reported NR-USN is less than or equal to the NR-U SN associated with the PDCP SN. 19.The apparatus of claim 16, where the information indicative of the rangeof data that has been successfully delivered to the terminal indicatesstart and end of an PDU NR-U SN set indicating whether the data in theset belongs to the feedback data to identify multiple PDCPs.
 20. Theapparatus of claims 17, wherein the processor is further configured to:determine whether all PDCP SN transmitted by the first network elementare less than or equal to the highest delivered PDCP SN in the feedbackdata; and determine whether all NR-U SN transmitted by the first networkelement are less than or equal to the highest reported NR-U SN in thefeedback data, where all transmitted data is successfully delivered tothe terminal based on a determination that all transmitted PDCP SN areless than or equal to the highest delivered PDCP SN and all transmittedNR-U SN are less than or equal to the highest reported NR-U SN.